HSE Occupational Health and Hygiene 4 — Questions and Answers
Question 1: Work in a confined space with oxygen concentration below what percentage is considered oxygen-deficient and requires supplied-air or SCBA?
- 16%
- 18%
- 19.5% (Correct answer)
- 21%
Correct answer: 19.5%
OSHA defines an oxygen-deficient atmosphere as one with less than 19.5% oxygen by volume, requiring respiratory protection that supplies breathable air.
Question 2: Heat stress risk is evaluated using which index that accounts for temperature, humidity, radiant heat, and air movement?
- Wet Bulb Globe Temperature (WBGT) (Correct answer)
- Heat Index (HI)
- Apparent Temperature Index
- Discomfort Index (DI)
Correct answer: Wet Bulb Globe Temperature (WBGT)
WBGT is the internationally recognized index for evaluating heat stress because it incorporates dry bulb temperature, natural wet bulb temperature, and globe temperature to account for all thermal environmental factors.
Question 3: Ionizing radiation exposure in the workplace is primarily regulated by which U.S. federal agency for general industry?
- Nuclear Regulatory Commission (NRC) for all workplaces
- OSHA under 29 CFR 1910.1096 (Correct answer)
- EPA under RCRA regulations
- Department of Energy under 10 CFR 835
Correct answer: OSHA under 29 CFR 1910.1096
OSHA regulates ionizing radiation exposure in general industry workplaces under 29 CFR 1910.1096, while the NRC regulates licensed radioactive materials.
Question 4: What is the primary purpose of a medical surveillance program in occupational health?
- To replace engineering controls once baseline health data is collected
- To detect early signs of work-related disease and evaluate effectiveness of exposure controls (Correct answer)
- To document pre-existing conditions for workers' compensation denial
- To determine if a worker's personal lifestyle causes their health complaint
Correct answer: To detect early signs of work-related disease and evaluate effectiveness of exposure controls
Medical surveillance programs detect early, subclinical health effects from occupational exposures, enabling early intervention and evaluating whether existing controls adequately protect workers.
Question 5: A worker develops contact dermatitis after handling a cutting fluid. Which route of exposure is most responsible?
- Inhalation of mist particles
- Dermal absorption through skin contact (Correct answer)
- Ingestion from hand-to-mouth transfer
- Injection through high-pressure fluid
Correct answer: Dermal absorption through skin contact
Contact dermatitis from cutting fluids is caused by direct skin contact (dermal route), leading to either irritant or allergic contact dermatitis.
Question 6: Which of the following best describes a 'ceiling limit' as used in occupational exposure standards?
- The maximum 8-hour time-weighted average concentration
- A concentration that should never be exceeded at any time during a work shift (Correct answer)
- The concentration at which 50% of workers experience adverse effects
- The upper boundary of the STEL averaging period
Correct answer: A concentration that should never be exceeded at any time during a work shift
A ceiling limit is a concentration that must not be exceeded at any moment during the workday, used for substances with immediate toxic effects.
Question 7: Occupational asthma is distinguished from pre-existing asthma aggravated by work by the fact that:
- Occupational asthma only occurs in workers over age 50
- Occupational asthma is caused or induced by a specific work-related exposure (Correct answer)
- Pre-existing asthma always resolves when the worker leaves employment
- Occupational asthma exclusively affects the upper respiratory tract
Correct answer: Occupational asthma is caused or induced by a specific work-related exposure
Occupational asthma is defined as asthma caused by sensitization or irritation from a specific agent encountered in the workplace, rather than pre-existing asthma that is merely worsened at work.
HSE Occupational Health and Hygiene 4
Work in a confined space with oxygen concentration below what percentage is considered oxygen-deficient and requires supplied-air or SCBA?